Electric treater

ABSTRACT

A resistance heater element is mounted in the shell of an electric emulsion treater close enough to the interface of collected oil and water bodies to effectively heat material at the interface. The heater is connected in the supply circuit of the transformer of the electric system of the treater.

United States Patent Prestridge et al.

[451 Sept. 16, 1975 ELECTRIC TREATER Inventors: Floyd L. Prestridge, Mounds; Harry G. Wallace, Jenks; Rex T. Meyers, Tulsa, all of Okla.

Combustion Engineering, Inc., New York, N.Y.

Filed: Feb. 19, 1974 Appl. No.: 438,986

Assignee:

US. Cl. 204/305; 204/186; 204/ 188; 204/185; 204/308 Int. Cl. B03C 5/02; C10G 33/02 Field of Search 204/164, 168, 186-191, 204/302-308 References Cited UNITED STATES PATENTS 4/1919 McKibben 204/305 1,304,786 5/1919 McKibben 204/305 1,405,123 1/1922 Harris 204/305 1,442,608 1/1923 Eddy 204/305 1,926,013 9/1933 Garrison 204/305 3,441,496 4/1969 Murdock, Sr 204/308 X 3,476,678 1 1/1969 Murdock, Sr 204/308 Primary ExaminerJohn H. Mack Assistant ExaminerAaron Weisstuch Attorney, Agent, or FirmArthur L. Wade [5 7] ABSTRACT A resistance heater element is mounted in the shell of an electric emulsion treater close enough to the interface of collected oil and water bodies to effectively heat material at the interface. The heater is connected in the supply circuit of the transformer 0f the electric system of the treater.

1 Claim, 1 Drawing Figure ELECTRIC TREATER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protection of a transformer from overloading and utilization of energy isolated from the transformer in a related process. More specifically, a transformer input is controlled by a resistive element and the conductivity of the circuit connected to the transformer secondary is influenced by the heat of the resistive element.

2. Description of the Prior Art It is customary to control the current to transformers from a source by either circuit breakers, fuses or some internal current limiting device. More specifically, transformers are often provided with a core designed with predetermined saturation or an external reactance which has a saturable core, both limiting the current in the primary of the transformer as the load of the secondary becomes more conductive.

Where the transformer is in a circuit serving a system in which the heat generated by control of the primary current can be used to advantage, it is generally impractical to adapt a reactive device to supply this heat. The heat of reactive devices of these transformers is generally wasted, unavailable for usage in the system served by the circuit.

The primary circuit can be controlled by resistance. In general, the effective resistance is more expensive than reactive devices and less efficient. The resistance generates more heat than reactive devices. However, the resistance unit can be mechanically positioned to effectively deliver its heat to specific locations in the system. Therefore, in many processes, the additional cost of the resistance device, compared to the reactive device, is more than offset by the efficient application of its heat which would otherwise be necessarily wasted by the reactive device. Obviously, with the resistive device connected continuously in series with the transformer primary, the delivery of additional heat becomes automatic as the conductance of the load in creases. Therefore, the transformer is protected from excessive primary current flow while the heat it generates is salvaged for work in the process.

SUMMARY OF THE INVENTION A principal object of the invention is to prevent a transformer primary from drawing excessive current from a source as the secondary load circuit increases in conductivity.

Another object is to isolate excess energy of a source from a transformer primary and use the heat in a process.

Another object is to control energy applied to the transformer of an electric emulsion treater so excessive energy will not be drawn from the line supply as the conductivity of the load circuit of the transformer increases and convert any excess energy from the line supply it had by a resistance unit which is placed so its heat will reduce the conductivity of a segment of the load ciruit.

The present invention is embodied in a system which supplies both thermal and electrical energy to a process. The process is carried out under the force of an electrostatic field established between electrodes con nected to the secondary of a transformer. A resistance element is connected between a supply and the trans former primary to limit the current drawn by an increasingly conductive segment of a circuit between the electrodes. The resistance element is placed relative to the circuit segment so the segment will have its temperature raised by the heat output of the element as the element limits the current to the transformer.

Other objects, advantages and features of this invention will become apparent to one skilled in the art upon consideration of the written specification, appended claims, and attached drawings, wherein;

The drawing is a somewhat diagrammatic side elevation of an electric emulsion treater embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, the essential elements of an electric emulsion treater are disclosed, including the structure in which the present invention is embodied. A cylindrical shell 1 is horizontally extended. An inlet 2 is the conduit into shell 1 for an emulsion of oil and water as produced from an oil well not shown.

Heat is a valuable factor in breaking an emulsion so it will separate into its components. A heater 3 is mounted in compartment 4 of shell 1 so it will be contacted by the emulsion and raise the temperature of the emulsion as required.

Arrows are used to indicate in a general way the flow of the emulsion over heater 3. If gas is initially present, or developed by the heating, it disengages from the emulsion and goes up. The compartment 4 is defined by a baffle 5 which extends vertically across the shell 1. A lower opening 6 in the baffle is a conduit for the emulsion liquids to flow from compartment 4. An upper opening 7 is a conduit for any gas disengaged from the emulsion liquids. Both fluids flow from com partment 4 into the remainder of the shell 1 volume which is designated compartment 8.

It is the convention to describe compartments such as 8 as the treating compartment of electric treaters. In general, an electrode system is mounted in these compartments. Energized, the electrode system establishes an electrostatic field wlhose force coalesces the water droplets of the emulsion with droplets of such size that they will gravitate to the bottom of the compartment.

Electrode 9 represents the electrode system. Electrical energy is supplied this electrode through connection to the secondary of a transformer 10. The result is to collect a body of water 11 beneath the electrode while the breaking emulsion body 12 forms above interface 13.

Oil of the breaking emulsion flows upward toward outlet 14. The water of body 11 flows downward toward outlet 15. Any gas which continues to evolve collects above the liquid to join that gas flowing from opening 7 and flow out shell 1 through outlet 16. Thus the overall process is completed.

However, there are many problems in operating these units. The art is replete with solutions to problems of distribution of fluids, connecting the electrode system and transformer safely and thermal control of the fluids. One of the more severe problems is protection of transformer 10.

The circuit to which transformer 10 is connected includes the path between the electrodes. Considering electrode 9 as one electrode, and the shell 1 as the other electrode, the path between these electrodes includes the breaking emulsion 12, the material at interface 13 and the coalesced water 11. This path is a load circuit of the secondary of transformer 10. If this path becomes sufficiently conductive it can draw so much current from the transformer that it will overheat the transformer and damage it physically. There have been myriads of devices and systems for overload protection of these transformers. The present invention not only protects the transformer but uses the heat generated to specific advantage in the treatment process of compartment 8.

In the drawing, transformer 10 is disclosed somewhat diagrammatically as having a secondary winding 20. One end of winding is connected to ground. The other end is connected to electrode 9. As the shell 1 is also grounded, an electrostatic field is developed between the electrode 9 and shell 1 as a load on transformer 10.

The energy supplied transformer 10 is applied to primary winding 21 from a source 22. Source 22 is connected to winding 21 through closure of switch 23.

A winding 24 is placed on the core of transformer 10 to monitor the output of transformer 10. A light 25 and/or a meter 26 responds to the energy induced into winding 24 so there will be a calculated, readable manifestation of the power transferred through the core of transformer 10 available to personnel operating the system.

Given source 22, connected to primary 21 through switch 23, energy will be drawn from the source through primary 21 in proportion to the conductivity of the path between the electrodes connected to the secondary. Specifically, as the conductivity of the material at the interface 13 increases, the more conductive the entire path becomes. When this segment of the path becomes sufficiently conductive, enough current will be drawn from transformer 10 to overheat and damage its windings and their insulation.

Although reference has been generally made to the electrostatic field between electrode 9 and shell 1, it is that specific portion of the field between electrode 9 and the body of water 11 which is of immediate concern. It is the force of this field which continually coalesces the droplets of water dispersed in the oil rising toward electrode 9. The body of water 11 becomes the effective electrode above which the field is established with electrode 9. It is in this volume that the treating, or coalescing, of water droplets and their separation from oil, takes place.

As emulsion flows into compartment 8, through opening 6, it may build up in a thickening layer at 13 because of various operating conditions in the process. This unresolved emulsion layer 13 is very conductive because of its high water content. The deeper the layer the more conductive this segment of the path becomes. Heat introduced specifically into layer 13 will be a force for resolving the emulsion, lowering the height of the layer, and, therefore, reducing the conductivity of this segment of the path.

Heater 30 represents structures with which heat can be introduced into layer 13 as a resolving force on the emulsion. More than one of these heaters can be mounted in this layer 13 to distribute heat effectively. The single heater 30 disclosed is only representative of any desired number of such structures.

In all events, heater 30 is essentially an electrical resistance included, as disclosed, in the circuit of source 22 and primary 21. As a resistance, heater 30 is disclosed as simply in series with primary 21 which is connected to source 22 by switch 23. As the energy drawn from source 22 increases, a portion of it is dissipated through heater 30. The results of this arrangement are the benefits of the invention.

Heater 30 brings about two beneficial results at the same time. First, as the path between the electrodes becomes more conductive the current drawn by transformer 10 increases. However, heater 30, in series with the primary winding 21, is sized to limit the amount of current so the winding 21 will not overheat and its insulation be damaged. Therefore, transformer 10 is protected against overload.

Second as the heater 30 dissipates the energy as heat it raises the temperature of the interface material at 13. This increase in temperature is a force to resolve the emulsion at interface 13 which results in decreasing the conductivity of this segment of the path. Therefore, the invention not only protects the transformer on this type of service but reduces the overload condition which threatens the transformer.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the invention.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted in an illustrative and not in a limiting sense.

The invention, having been described, what is claimed is:

l. A System for supplying thermal and electrical energy for dehydrating oil field emulsions, including:

a. A Shell connectable to a supply of produced oil field emulsion and in which the emulsion is treated into oil and water,

b. compartment means within said shell and containing an electrode system adapted to provide an electrostatic field for forming an oil-water interface in said compartment,

c. a transformer connected by its secondary to said electrode system,

d. a supply of electrical energy connected to the pri-' mary of said transformer,

e. and a resistance heating element electrically connected in series circuit with said primary of said transformer and said supply of electrical energy and adapted to be positioned at said oil-water interface in said compartment,

whereby an increase in conductivity in the electrode system first causes an increase in current flow which is limited by the included resistance heating element while the resulting increase in thermal output from the resistance heating element into the material at the in terface then causes a lowering of the conductivity in the electrode system. 

1. A SYSTEM FOR SUPPLYING THERMAL AND ELECTRICAL ENERGY FOR DEHYDRATING OIL FIELD EMULSION, INCLUDING: A. A SHELL CONNECTABLE TO A SUPPLY OF PRODUCED OIL FIELD EMULSION AND IN WHICH THE EMULSION IS TREATED INTO OIL AND WATER, B.COMPARTMENT MEANS WITHN SAID SHELL AND CONTAINING AN ELECTRODE SYSTEM ADAPTED TO PROVIDE AN ELECTROSTATIC FIELD FOR FORMING AN OIL-WATER INTERFACE IN SAID COMPARTMENT, C. A TRANSFORMER CONNECTED BY ITS SECONDARY TO SAID ELECTRODE SYSTEM, D. A SUPPLY OF ELECTRICAL ENERGY CONNECTED TO THE PRIMARY OF SAID TRANSFORMER, E. AND A RESISTANCE HEATING ELEMENT ELECTRICALLY CONNECTED IN SERIES CIRCUIT WITH SAID PRIMARY OF SAID TRANSFORMER AND SAID SUPPLY OF ELECTRICAL ENERGY AND ADAPTED TO BE POSITIONED AT SAID OIL-WATER INTERFACE IN SAID COMPARTMENT, WHEREBY AN INCREASE IN CONDUCITIVITY IN THE ELECTRODE SYSTEM FIRST CAUSES AN INCREASE IN CURRENT FLOW WHICH IS LIMITED BY THE INCLUDED RESISTENCE HEATING ELEMENT WHILE THE RESULTING INCREASE IN THERMAL OUTPUT FROM THE RESISTANCE HEATNG ELEMENT INTO THE MATERIAL AT THE INETRFACE THEN CAUSES A LOWERING OF THE CONDUCTIVITY IN THE ELECTRODE SYSTEM. 